1. Field of the Invention
The present invention relates to a multi-transmission/reception antenna device and a multi-transmission/reception method in a multi-user and multi-cell environment for uplink and downlink. In particular, the present invention relates to a multi-transmission/reception antenna device and a multi-transmission/reception method in a multi-user and multi-cell environment that can appropriately select a user using channel response information of a user to be selected in a cell and information of interference signals from adjacent cells.
2. Description of the Related Art
In general, a wireless communication system that uses a multi-transmission/reception antenna is a communication system that has been developed in order to achieve a large-bit transfer rate in a limited bandwidth. In such a wireless communication system, a multi-antenna is used at a transmission/reception terminal, and an appropriate transceiver structure is adopted accordingly, thereby achieving a high transfer rate. At this time, the transmitting unit multiplies individual items of a signal vector to be transmitted by individual allocated power values, and multiplies the signal vector multiplied by the allocated power values by a weighted matrix of a transmission antenna again. The receiving unit also multiplies the individual items of the transmitted signal vector by an appropriate weighted matrix so as to generate a plurality of subchannels in a space domain. Independent data streams can be transmitted through the individual subchannels.
In a known multi-transmission/reception antenna system, a technology that assumes a one-to-one wireless communication system having a pair of transceivers is applied, leaving presence of other cells generating interference signals out of consideration. In addition, in order to achieve a higher transfer rate, a multi-user multi-transmission/reception antenna system that can obtain advantages of multiplexing of a multi-user environment has been researched for an uplink (K.-N. Lau, “Analytical framework for multiuser uplink MIMO space-time scheduling design with convex utility functions,” IEEE Transactions on Wireless Communications, vol. 3, no. 5, September 2004) and a downlink (O.-S. Shin, and K. B. Lee, “Antenna-assisted round robin scheduling for MIMO cellular systems,” IEEE Communications Letters, vol. 7, no. 3, pp. 109-111, March 2003).
However, a research on an existing multi-user multi-transmission/reception antenna system has a limitation in that a single cell environment is taken into consideration, but an influence by an interference signal from adjacent cells in an actual mobile communication environment is not taken into full consideration.
Meanwhile, unlike the multi-user environment, for a single user environment, a research on an influence of an interference signal from adjacent cells has progressed. Blum has researched downlink performance when a transmission method is determined in consideration of the interference signal from adjacent cells in a multi-cell environment (R. S. Blum, “MIMO capacity with interference,” IEEE Journal on Selected Areas in Communications, vol 21, no. 5, pp. 793-801, June 2003). (In this paper, a research has progressed in a multi-link environment, not a multi-cell environment, but, when a cell structure of a cellular system is applied to a multi-link environment, it is regarded as a multi-cell environment.) Further, Dai et al have suggested a receiver system that takes an influence of interference from adjacent cells into consideration in a downlink multi-transmission/reception antenna environment where interference from adjacent cells exist (H. Dai, A. F. Molisch, and H. V. Poor, “Downlink capacity of interference-limited MIMO systems with joint detection, IEEE Transactions on Wireless Communications, vol. 3, no. 2, March 2004).
However, the researches of Blum and Dai et al assume only downlink case and are limited to the case which assumes single user in each cell. Researches on the influence of an interference signal from adjacent cells for uplink multiuser systems are insufficient.